GAS THERMAL OIL HEATER SELECTION
How to Select a 2–12 Million kcal/h Gas-Fired Thermal Oil Heater
Select a gas-fired thermal oil heater from process duty, supply and return temperatures, thermal-fluid limits, circulation flow, pressure drop and the complete expansion, pumping, control and heat-recovery system.
QUICK ANSWER
Convert the process duty, then protect flow and fluid temperature.
Capacity
1 million kcal/h equals approximately 1.163 MW. JIELI’s published YY(Q)L range covers 200–1200 ×10⁴ kcal/h, with rounded nominal ratings from 2.4 to 14 MW.
Temperature
Specify supply, return, startup and upset temperatures. Check both bulk-fluid and film-temperature limits with the selected heat-transfer fluid supplier.
Circulation
Calculate flow from heat duty, fluid heat capacity and temperature difference, then verify density, viscosity, coil velocity, system pressure drop and pump NPSH.
Do not size only from kcal/h: two plants with the same duty can require different heaters, pumps, pipe sizes and expansion volumes.
01 · HEAT DUTY
Separate steady production from startup and simultaneous peaks.
List steady duty, warm-up energy and time, heat losses and simultaneous operation for each process user. Check both peak duty and minimum sustained load.
1 million kcal/h = approximately 1.163 MW = 3.97 MMBtu/h.
Use one conversion basis. Manufacturer model tables may use rounded nominal capacities; retain the stated units and compare actual guaranteed output.
02 · TEMPERATURE AND FLUID
Bulk-fluid temperature is not the same as film temperature.
Specify supply and return temperatures. Select fluid for the required temperature range, cold viscosity, vapor pressure, compatibility and bulk/film limits.
The fluid next to the heated coil wall can be hotter than the measured bulk outlet. Insufficient flow, fouling or excessive heat flux can raise this film temperature and accelerate degradation. Eastman’s thermal-fluid design guidance emphasizes matching heater capacity, temperature and fluid velocity and using adequate turbulent flow to avoid hot spots.
03 · CIRCULATION
Calculate flow from duty and ΔT, then verify the real hydraulic loop.
For preliminary liquid-phase sizing:
ṁ = Q ÷ (cp × ΔT)
Volume flow = mass flow ÷ density
Use fluid properties at operating temperature. Sum coil, user, pipe, valve and strainer losses for pump differential head. In a filled closed loop, elevation does not add continuous pump head, but it affects local pressure and NPSH. Check cold viscosity and minimum flow as users close.
Calculate using the thermal oil flow-rate and pipe-size calculation guide, then check the pump with the thermal oil circulation pump selection guide.
04 · YY(Q)L PRELIMINARY RANGE
Match capacity to published flow and main-pipe data.
These preliminary values come from JIELI’s product table. Recalculate flow and pipe size for the selected fluid and circuit losses. For model terminology, see the YYW, YYL, YLW and YGL model guide.
| Model | Rated capacity | Nominal power | Circulation flow | Main pipe |
|---|---|---|---|---|
| YY(Q)L-200 | 200 ×10⁴ kcal/h | 2,400 kW | 160 m³/h | DN200 |
| YY(Q)L-240 | 240 ×10⁴ kcal/h | 2,800 kW | 200 m³/h | DN200 |
| YY(Q)L-300 | 300 ×10⁴ kcal/h | 3,500 kW | 200 m³/h | DN200 |
| YY(Q)L-350 | 350 ×10⁴ kcal/h | 4,100 kW | 250 m³/h | DN250 |
| YY(Q)L-400 | 400 ×10⁴ kcal/h | 4,600 kW | 250 m³/h | DN250 |
| YY(Q)L-500 | 500 ×10⁴ kcal/h | 6,000 kW | 300 m³/h | DN250 |
| YY(Q)L-600 | 600 ×10⁴ kcal/h | 7,000 kW | 400 m³/h | DN250 |
| YY(Q)L-700 | 700 ×10⁴ kcal/h | 8,200 kW | 400 m³/h | DN300 |
| YY(Q)L-800 | 800 ×10⁴ kcal/h | 9,300 kW | 500 m³/h | DN300 |
| YY(Q)L-900 | 900 ×10⁴ kcal/h | 10,500 kW | 500 m³/h | DN300 |
| YY(Q)L-1000 | 1000 ×10⁴ kcal/h | 12,000 kW | 500 m³/h | DN350 |
| YY(Q)L-1200 | 1200 ×10⁴ kcal/h | 14,000 kW | 600 m³/h | DN400 |
Published maximum working temperature is 320°C and rated working pressure is 1.0 MPa for this preliminary range. Final design conditions depend on the thermal fluid, system static head, pump pressure, code and project safety margin.
05 · COMPLETE LOOP
The heater is one component of the thermal-fluid system.
| System item | Selection question | Failure to avoid |
|---|---|---|
| Circulation pumps | Can the pumps maintain minimum heater flow at hot and cold conditions? | Low flow, cavitation or coil overheating |
| Expansion tank | Does volume cover the fluid density change with correct cold and hot levels? | Overflow, low suction head or air contact |
| Process users | How do valves and bypasses behave as users open and close? | Unstable system flow |
| Controls | Are low-flow, high-temperature, pressure and flame trips independent and testable? | Unsafe continued firing |
| Piping | Is expansion flexibility, venting, draining and leak management engineered? | Stress, trapped gas or fluid leakage |
Size usable expansion volume from the fluid’s density change. Tank elevation and connection to pump suction affect suction pressure and venting. See the expansion tank sizing guide.
06 · GAS AND EFFICIENCY
State the gas basis and evaluate efficiency across the load range.
Specify gas composition, pressure, LHV/HHV, reference volume and emissions. Check burner turndown at minimum duty and fan capacity against furnace and duct resistance at site conditions.
Gas flow equals useful duty divided by efficiency and heating value, using consistent LHV/HHV bases. Account separately for startup, standby and part load. See the gas boiler and heater fuel-consumption guide.
Data required for a 2–12 million kcal/h gas thermal oil heater proposal
- Process duty by user, warm-up time, simultaneous load and future allowance;
- Thermal-oil supply, return, startup and maximum upset temperatures;
- Selected fluid name, property data and bulk/film temperature limits;
- Total system volume, elevation, pressure drop and required circulation philosophy;
- Natural-gas pressure, composition, LHV/HHV and emissions limits;
- Site altitude, ambient range, plot plan and transport constraints;
- Expansion, storage, pumps, controls, heat recovery and documentation scope.
TECHNICAL REFERENCES
Primary fluid guidance and related engineering pages.
- Eastman Therminol — Heat-transfer system design resources
- Eastman Therminol — Liquid-phase heat-transfer system design guide
- JIELI — Complete thermal oil heater selection guide
- JIELI — Published YY(Q)L-200 to YY(Q)L-1200 preliminary range
Confirm model data through a project heat balance, hydraulic calculation and agreed performance conditions.
FREQUENTLY ASKED QUESTIONS
Large gas-fired thermal oil heater FAQ
How many MW is 2 million kcal/h?
Using the physical conversion, 2 million kcal/h is approximately 2.326 MW. A manufacturer’s nominal model table may show rounded kW values, so use the published capacity rows consistently.
How is thermal-oil circulation flow calculated?
Divide useful heat duty by the product of thermal-fluid specific heat and the selected supply-return temperature difference to obtain mass flow, then divide by density for volume flow. Verify the result against coil velocity, pressure drop and cold-start viscosity.
Is 320°C suitable for every heat-transfer fluid?
No. The heater design condition and the selected fluid’s bulk and film temperature limits must both be checked. Fluid condition, flow, heat flux and upset protection also affect safe operation.
Why does a thermal oil system need an expansion tank?
The fluid changes volume with temperature. The expansion system must accommodate that change, provide a stable inventory and pump suction condition, support venting and limit unnecessary contact with air where required by the fluid supplier.
Can a hot oil boiler be selected only by kcal/h?
No. Temperature range, thermal-fluid properties, circulation, coil velocity, pressure drop, burner turndown, expansion volume, controls and site conditions are also required.
JIELI THERMAL ENGINEERING
Turn process duty into a complete thermal-fluid system specification.
Provide heat duty, temperatures, fluid data, gas specification, system volume, location and supply scope.
Request a thermal oil heater selection